The access to clean water is vital to humans and animals and water is today a shortage commodity in large parts of the world due to increased population, changes in the way we live, increased use of water for irrigation.
Primary sources for fresh water are ground water, rivers and lakes. Here the water is free from salt and needs only to be purified from dirt and microbes through low energy demanding processes to be applicable for drinking water or in agriculture. Countries that lack the possibility to further explore the ground water and which lack other exploitable natural fresh water reserves must get their fresh water from the sea. Before the seawater can be used by humans as drinking water or for irrigation in agriculture it must first be desalted using an energy demanding desalting process. The energy source is today based on fossil fuels which cause environmental damages in the form of pollution and enhanced global warming. Additionally, the desalting process produces high salt concentrated rest products which are very toxic for both plants and animals.
An alternative way of circumventing the lack of access to fresh water is to take advantage of the water found in the air. There are today several known and available techniques to condense water from air. These techniques are usually based on hygroscopic material which binds the moisture in the air. The water can then be retained from the hygroscopic material in liquid form by using heating and cooling in various cycles. The heating and cooling respectively of the air in these processes demand relatively large amount of energy. They are therefore not a competitive alternative to large scale production of fresh water from sea water.
Prior art contains several different approaches to extract water from air. DE102006038983 relates to a method using a fluid sorbent with a hygroscopic salt and a pressure generating unit. CN101100866 and RU2230858 both describe systems that require various cooling systems while WO9907951 relates to a system with a vacuum pump that discharges steam to a condenser. U.S. Pat. No. 2,138,689 relates to a method for gaining water from the atmosphere by exposing wood to air during the night. The wood is then placed in a closed space where the air and the wood are warmed up by the sun. The warmed air is saturated with moisture and the air flows through a channel to a condenser and the liquidized water is then collected. The air returns to the closed space to take up more moisture.